These wonderful yellow composites are actually called Swamp Sunflowers, helianthus angustifolius, and can be seen along the backroads of rural Georgia blooming profusely this time of year. My first recollection of them was probably about 15-20 years ago when my friend Joani and I were travelling miles and miles to Goodness Grows, our favorite perennial nursery. We saw the wonderful Swamp Sunflowers everywhere, and were very surprised and delighted when we spotted them for sale in huge buckets at Goodness Grows. I've planted them along the creek that runs into "our" lake and am always delighted when they burst into bloom!
I also love Ironweed, which brings back fond, fond memories of summer vacations spent along the Greenbrier River in West Virginia with C's family. I think the purple and yellow make a great combination (even if they are blurred this morning!).
What makes you know that it's Fall/Autumn? I'm curious, so please share!